Original Research ARTICLE
Negative thermal expansion near the precipice of structural stability in open perovskites
- 1University of Connecticut, United States
- 2Centro de Investigacio ́n en Ciencia e Ingenier ́ıa de Materiales and Escuela de F ́ısica, Universidad de Costa Rica, Costa Rica
Negative thermal expansion (NTE) describes the anomalous propensity of materials to shrink when heated. Since its discovery, the NTE effect has been found in a wide variety of materials with an array of magnetic, electronic and structural properties. In some cases, the NTE originates from phase competition arising from the electronic or magnetic degrees of freedom but we here focus on a particular class of NTE which originates from intrinsic dynamical origins related to the lattice degrees of freedom, a property we term structural negative thermal expansion (SNTE). Here we review some select cases of NTE which strictly arise from anharmonic phonon dynamics, with a focus on open perovskite lattices. We find that NTE is often present close in proximity to competing structural phases, with structural phase transition lines terminating near T=0 K yielding the most prominent displays of the SNTE effect. We further provide a theoretical model to make precise the proposed relationship among the signature behavior of SNTE, the proximity of these systems to structural quantum phase transitions and the effects of phase fluctuations near these unique regions of the structural phase diagram. The effects of compositional disorder on NTE and structural phase stability in perovskites are discussed.
Keywords: Negative thermal expansion, Structural negative thermal expansion, quantum phase transition, structural phase transition, perovskite, antiferrodistortive phase transition, scandium trifluoride
Received: 14 Jul 2018;
Accepted: 19 Oct 2018.
Edited by:Andrea Sanson, Dipartimento di Fisica e Astronomia, Università degli Studi di Padova, Italy
Reviewed by:Fengxia Hu, Institute of Physics (CAS), China
Ranjan Mittal, Bhabha Atomic Research Centre, India
Copyright: © 2018 Occhialini, Guzman-Verri, Handunkanda and Hancock. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Jason Hancock, University of Connecticut, Mansfield, United States, email@example.com